1. Field of the Invention
The present invention relates generally to a sensor arrangement for an engine, and more particularly to an improved sensor arrangement for a split-bank, multicylinder engine.
2. Description of Related Art
In all fields of engine design, there is increasing emphasis on obtaining high performance in output and more effective emission control. This trend has resulted in employing, for example, a fuel injected, multi-cylinder, four-cycle engine. The engine can have a direct or indirect fuel injection system and multiple cylinders such as, for example, six cylinders arranged in V-configuration. The fuel injection system enables the engine to be more responsive to operator demand, which may rapidly change. For example, the operator may desire that the engine rapidly accelerate and then rapidly decelerate within a short period of time. Fuel injection is an advantageous manner to achieve fuel economy and responsiveness under such engine operating conditions.
The fuel injection system and other sophisticated electrical devices associated with the engine require a high performance control system, which can include a control unit such as, for example, an electronic control unit (ECU), and various sensors that can sense the operator's demands and surrounding conditions; both of which can rapidly change. Sensors may be employed that sense a condition of intake air within the intake passages to detect the operator's demands and the proper amount of fuel for injection. Several sensors are available for this purpose.
An intake air pressure sensor is one such sense. The pressure sensor senses an intake air pressure within the intake passages. The signal sensed by the intake pressure sensor is highly important to determining a proper amount of fuel for injection. Engine speed is also important to this analysis. A crankshaft angle position sensor can be used to sense engine speed. In addition, a throttle valve position sensor is another important sensor in evaluating operator demands. The throttle valves typically are operable by the operator to control the engine speed or torque of the engine. That is, the opening degree of the throttle valves can vary in response to a movement of a throttle lever which can be operated by the operator when he or she desires to accelerate or decelerate the engine operation. The signal sensed by the throttle valve position sensor can be used for increasing or decreasing the injected fuel amount in response to the acceleration demand or deceleration demand, respectively. For example, JP Laid Open No. 9-88623 (corresponding to U.S. Pat. No. 5,829,402) discloses such an intake air pressure sensor (50) and an throttle valve position sensor (57).
With the V-configured, multi-cylinder, four-cycle engine, all of the intake air relating sensors typically are arranged on the intake conduits on a single side so that maintenance service can be more easily performed. This arrangement, however, increases the possibility of damage to all of the related sensors when something damages a portion of the engine on this side. The problem is serious with outboard motors, which of course can employ such an engine, because a cowling assembly made of plastic typically is the only protection for the engine.
A need therefore exists for an improved sensor arrangement for an engine that can decrease possibility of damage to all of the sensors that sense a condition of intake air.